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Billions and billions! Using data from a solar system detected by the Kepler space telescope, astronomers now extrapolate that there are at least as many planets as stars in our galaxy.

2 comments

Very interesting – I think it’s been trending this way for some time – i.e., planets are common & most stars have them, and we were only waiting for the “proof”, so to speak. I’m pretty confident the 100 Billion number is an extremely conservative estimate – when all’s said & done, it will probably turn out that the total number of planets will be 4, 5 or more times the number of stars. We can be almost certain that of the planetary systems we know about, there are probably additional (smaller) planets in the system that have yet to be discovered. Also, wasn’t there recently a story we saw here about a “wandering” planet that wasn’t orbiting any star, just drifting on its own thru space? And it’s unlikely we’d just happen to be “lucky” enough to find such an oddity – most lkely, there are billions more like it. Exciting times! Personally, I believe the day is not far off when it will be announced we’ve discoverd a planet with nearly earth-like conditions (size, mass, composition) orbiting a Sun-like star in the habitable zone, and with all the conditions necessary to support life as we know it. Little Green Men, anyone?

From what I’ve read, it was pretty much accepted that other stars had planets almost from the time it was understood that planets were worlds more or less like our own and stars were just distant suns. It was more the logic of it since direct observation of other stars’ planets was impossible: our sun didn’t seem to be special, so if it was typical, other stars would have planets, too. I’ve seen the existence of other stars’ planets accepted as a matter of course in a very early novelette (1744) about a trip to Mars, and it goes back much further. But since there was no actual proof of such planets, it was more a matter of abstract reasoning if not faith.
However, it wasn’t clear how planets would form in the first place, so there was a competing theory prominent early in the 20th Century (I’ve seen it particularly in circa 1930s literature) that planet formation might actually be very rare, the result of two stars passing each other very closely and pulling out streams of material from each other that later coalesced into planets. Since stars practically never came that close to each other, there might be only two stars with planets in the entire galaxy: ours and whatever star had passed the sun, long since disapppeared in the eternal darkness. Who dared fondly cherish the hope that nearly every star had planets when the learned savants disputed it? As it turned out, the more faith than reason view that stars simply *had* to have planets was correct.

“Not simply about one mission, [Genesis] is also the history of America’s quest for the moon… Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America’s greatest human triumphs.” –San Antonio Express-News